steering wheel DODGE NEON 2000 Service Service Manual

(4) Install the caliper guide pin bolts and tighten
them to a torque of 22 N´m (192 in. lbs.) (Fig. 57).
(5) Install the banjo bolt connecting the brake hose
to the brake caliper (Fig. 56). Place one fitting
washer on each side of the hose fitting as the banjo
bolt is guided through the fitting. Install new wash-
ers if they are worn or damaged at all. Thread the
banjo bolt into the caliper and tighten it to a torque
of 48 N´m (35 ft. lbs.).
(6) Install the tire and wheel assembly. Tighten
the wheel mounting nuts to a torque of 135 N´m (100
ft. lbs.).
(7) Lower the vehicle.
(8) Remove the brake pedal holding tool.
(9) Bleed the caliper as necessary. Refer to BASE
BRAKE BLEEDING in the SERVICE PROCE-
DURES section in this service manual group.
(10) Road test the vehicle and make several stops
to wear off any foreign material on the brakes and to
seat the brake pads.
DISC BRAKE SHOES (FRONT)
NOTE: Before proceeding with this procedure,
review SERVICE WARNINGS AND CAUTIONS at the
beginning of REMOVAL AND INSTALLATION in this
section.
NOTE: Vehicles that are equipped with optional
Four-wheel-disc brake system use a different lining
material on the front disc brake shoes than vehicles
with front disc and rear drum brakes. When new
brake shoes are installed, be sure the brake shoes
for the correct type of brake system are used.
REMOVAL
(1) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE group for the
proper lifting procedure.
(2) Remove both front tire and wheel assemblies
from vehicle.
(3) Begin on one side of the vehicle.
(4) Remove the two brake caliper guide pin bolts
(Fig. 59).
(5) Remove the disc brake caliper from the steer-
ing knuckle. The caliper is removed by first tipping
either the top (right side caliper) or bottom (left side
caliper) of the caliper away from the brake rotor,
then pulling the caliper off the opposite end's caliper
slide abutment (on the knuckle) and brake rotor.
(6) Support the caliper using a wire or cord to pre-
vent the weight of caliper from damaging the brake
hose (Fig. 60). Do not let the caliper hang by the
brake hose.
Fig. 59 Caliper And Rotor Mounting
1 ± RETAINER CLIP
2 ± BRAKE ROTOR
3 ± HUB
4 ± GUIDE PIN BOLTS
5 ± DISC BRAKE CALIPER
Fig. 60 Supporting Caliper
1 ± WIRE HANGER
2 ± STEERING KNUCKLE
3 ± BRAKE DISC
4 ± DISC BRAKE CALIPER ASSEMBLY
5 ± BRAKE HYDRAULIC HOSE
PLBRAKES 5 - 35
REMOVAL AND INSTALLATION (Continued)

(7) Install the disc brake caliper (with pads) on the
brake rotor and steering knuckle. The left side cali-
per is installed by first sliding the top of the caliper
past the top caliper slide abutment on the steering
knuckle to hook the top edge of the caliper, then
pushing the lower end of the caliper into place
against the knuckle (Fig. 65). The right side caliper
is installed by first sliding the bottom edge of the cal-
iper past the lower caliper slide abutment on the
steering knuckle to hook the lower edge of the cali-
per, then pushing the top of the caliper into place
against the steering knuckle.(8) Install the caliper guide pin bolts and tighten
them to a torque of 22 N´m (192 in. lbs.) (Fig. 59).
(9) Install the tire and wheel assembly. Tighten
the wheel mounting nuts to a torque of 135 N´m (100
ft. lbs.).
(10) Repeat the above procedure to the front
brakes on the other side of the vehicle.
(11) Lower the vehicle.
(12) Pump the brake pedal before moving the vehi-
cle to set the brake shoes to the brake rotor.
(13) Road test the vehicle and make several stops
to wear off any foreign material on the brakes and to
seat the brake pads.
BRAKE ROTOR (FRONT)
REMOVAL
(1) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE group for the
proper lifting procedure.
(2) Remove the front tire and wheel assembly.
(3) Remove the front disc brake caliper assembly
from the brake rotor and store it out of the way.
Refer to DISC BRAKE SHOES (FRONT) in this
REMOVAL AND INSTALLATION section of this ser-
vice manual group.
(4) Remove the clips retaining the brake rotor (Fig.
59).
(5) Remove the brake rotor by pulling it straight
off the wheel mounting studs.
INSTALLATION
(1) Install the brake rotor over the wheel mount-
ing studs and onto the hub (Fig. 59).
(2) Install the front disc brake caliper. It may be
necessary to retract the brake caliper piston back
into the caliper to fit the shoes onto the rotor, if a
new rotor is being installed. Refer to DISC BRAKE
SHOES (FRONT) in this REMOVAL AND INSTAL-
LATION section of this service manual group.
(3) Install the tire and wheel assembly. Tighten
the wheel mounting nuts to a torque of 135 N´m (100
ft. lbs.).
(4) Lower the vehicle.
(5) Pump the brake pedal before moving the vehi-
cle to set the brake shoes to the brake rotor.
Fig. 64 Installing Outboard Brake Shoe
1 ± BRAKE SHOE ASSEMBLY
2 ± BRAKE CALIPER
Fig. 65 Installing Left Caliper
1 ± SLIDE TOP OF BRAKE CALIPER UNDER TOP ABUTMENT
OF STEERING KNUCKLE AS SHOWN
2 ± BRAKING DISC
3 ± DISC BRAKE CALIPER
4 ± STEERING KNUCKLE BRAKE ABUTMENT
PLBRAKES 5 - 37
REMOVAL AND INSTALLATION (Continued)

DISC BRAKE CALIPER (REAR)
REMOVAL
(1) Using a brake pedal holding tool as shown (Fig.
66), depress the brake pedal past its first one inch of
travel and hold it in this position. This will isolate
the master cylinder from the brake hydraulic system
and will not allow the brake fluid to drain out of the
master cylinder reservoir while the lines are discon-
nected.
(2) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE group for the
proper lifting procedure.
(3) Remove the rear tire and wheel assembly.
(4) Remove the banjo bolt connecting the brake
hose to the brake caliper (Fig. 67). There are two
washers (one on each side of the flex hose fitting)
that will come off with the banjo bolt. Inspect and
discard these if they are worn or damaged.
(5) Remove the two caliper guide pin bolts (Fig.
68).
(6) Remove the caliper assembly from the brake
adapter by first rotating the top of the caliper away
from the rotor, and then lifting the caliper assembly
off the machined abutment on the adapter (Fig. 69).
INSTALLATION
NOTE: Step (1) below is only required when install-
ing the disc brake caliper after new brake shoes
have been installed.
Fig. 66 Brake Pedal Holding Tool
1 ± CLUTCH PEDAL (IF EQUIPPED WITH MANUAL TRANSAXLE)
2 ± THROTTLE PEDAL
3 ± BRAKE PEDAL HOLDING TOOL
4 ± STEERING WHEEL
5 ± DRIVER'S SEAT
6 ± BRAKE PEDAL
Fig. 67 Brake Hose Mounting
1 ± BRAKE HOSE
2 ± GUIDE PIN BOLTS
3 ± CALIPER
4 ± BOLT
Fig. 68 Caliper Mounting
1 ± DISC BRAKE CALIPER
2 ± DISC BRAKE ADAPTER
3 ± GUIDE PIN BOLTS
4 ± HUB AND BEARING
5 ± BRAKE ROTOR
6 ± RETAINER CLIP
7 ± DUST CAP
8 ± NUT
5 - 38 BRAKESPL
REMOVAL AND INSTALLATION (Continued)

REMOVAL
(1) Using a brake pedal holder, depress the brake
pedal past its first one inch of travel and hold it in
this position (Fig. 75). This will isolate the master
cylinder from the brake hydraulic system and will
not allow the brake fluid to drain out of the master
cylinder reservoir.
(2) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE group for the
proper lifting procedure.
(3) Remove the rear tire and wheel assembly.
(4) Disconnect the rear brake flex hose from the
wheel cylinder (Fig. 76).
(5) Remove the rear brake drum.
(6) Remove the rear brake shoes from the brake
support plate. Refer to DRUM BRAKE SHOES in
this REMOVAL AND INSTALLATION section.
NOTE: If the brake shoes are wet with grease or
brake fluid, replace them.
(7) Remove the brake wheel cylinder attaching
bolts (Fig. 76).
(8) Remove the brake wheel cylinder from the
brake support plate (Fig. 77).
INSTALLATION
(1) Install a new O-ring at the mating surface of
the wheel cylinder-to-brake support plate (Fig. 77).NOTE: When installing wheel cylinder on brake
support plate, be sure it is positioned squarely (hor-
izontal) to the brake assembly.
(2) Install the wheel cylinder onto brake support
plate (Fig. 77). Tighten the attaching bolts to a
torque of 13 N´m (115 in. lbs.).
(3) Hand start the rear brake flex hose tube fitting
to wheel cylinder. Tighten the tube nut to a torque of
17 N´m (145 in. lbs.).
(4) Install the rear brake shoes on the brake sup-
port plate. Replace them as necessary.
(5) Install the rear brake drum onto the rear hub.
Fig. 75 Brake Pedal Holder
1 ± CLUTCH PEDAL (IF EQUIPPED WITH MANUAL TRANSAXLE)
2 ± THROTTLE PEDAL
3 ± BRAKE PEDAL HOLDING TOOL
4 ± STEERING WHEEL
5 ± DRIVER'S SEAT
6 ± BRAKE PEDAL
Fig. 76 Brake Flex Hose At Wheel Cylinder
1 ± BRAKE SUPPORT PLATE
2 ± WHEEL CYLINDER ATTACHING BOLTS
3 ± REAR BRAKE FLEX HOSE TUBE
4 ± WHEEL CYLINDER ASSEMBLY
Fig. 77 Remove/Install Wheel Cylinder
1 ± WHEEL CYLINDER
2 ± SUPPORT PLATE
3 ± O-RING
5 - 42 BRAKESPL
REMOVAL AND INSTALLATION (Continued)

(4) Remove the brake drum (Fig. 87).
NOTE: If the drum does not come off, further brake
clearance can be obtained by backing off the brake
automatic adjuster screw. Remove the rubber plug
from the top of brake support plate. Rotate the
automatic adjuster screw in an upward motion,
using a screwdriver.
INSTALLATION
NOTE: Before installing the drum, inspect the brake
shoe linings for wear, shoe alignment, and contam-
ination.
(1) Install the rear brake drum on rear hub and
bearing (Fig. 87).
(2) Install the tire and wheel assembly. Tighten
the wheel mounting nuts to a torque of 135 N´m (100
ft. lbs.).
(3) Adjust the rear brake shoes as necessary. Refer
to ADJUSTMENTS in this section of this service
manual group.
(4) Lower the vehicle.
DRUM BRAKE SHOE SUPPORT PLATE (REAR)
NOTE: Before proceeding with this procedure,
review SERVICE WARNINGS AND CAUTIONS at the
beginning of REMOVAL AND INSTALLATION in this
section.
REMOVAL
(1) Using a brake pedal holding tool as shown (Fig.
88), depress the brake pedal past its first one inch of
travel and hold it in this position. This will isolate
the master cylinder from the brake hydraulic system
and will not allow the brake fluid to drain out of the
master cylinder reservoir.
(2) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE group for the
proper lifting procedure.
(3) Remove the rear tire and wheel assembly from
the vehicle.
(4) Disconnect the rear brake flex hose from the
wheel cylinder (Fig. 89).
(5) Remove the rear brake drum.
(6) Remove the dust cap (Fig. 90) from the rear
hub and bearing.
(7) Remove the nut (Fig. 91) holding the rear hub
and bearing to the spindle. Remove the hub and
bearing from the spindle.
(8) Remove the rear brake shoes from the brake
support plate. Refer to DRUM BRAKE SHOES in
this REMOVAL AND INSTALLATION section.(9) Remove the parking brake actuator lever from
the parking brake cable.
(10) Position a 1/2 inch wrench over the retainer
fingers on the end of the parking brake cable (Fig.
92). Compress the cable housing retaining fingers
with the wrench, then pull the cable housing out of
the support plate. Remove the wrench as the parking
brake cable retainer is freed from the mounting hole
in the brake support plate.
Fig. 88 Brake Pedal Holding Tool
1 ± CLUTCH PEDAL (IF EQUIPPED WITH MANUAL TRANSAXLE)
2 ± THROTTLE PEDAL
3 ± BRAKE PEDAL HOLDING TOOL
4 ± STEERING WHEEL
5 ± DRIVER'S SEAT
6 ± BRAKE PEDAL
Fig. 89 Brake Flex Hose At Wheel Cylinder
1 ± BRAKE SUPPORT PLATE
2 ± WHEEL CYLINDER ATTACHING BOLTS
3 ± REAR BRAKE FLEX HOSE TUBE
4 ± WHEEL CYLINDER ASSEMBLY
5 - 46 BRAKESPL
REMOVAL AND INSTALLATION (Continued)

SPECIFICATIONS
BRAKE FLUID
The brake fluid used in this vehicle must conform
to DOT 3 specifications and SAE J1703 standards.
No other type of brake fluid is recommended or
approved for usage in the vehicle brake system. Use
only Mopar brake fluid or an equivalent from a
tightly sealed container.
CAUTION: Never use reclaimed brake fluid or fluid
from an container which has been left open. An
open container will absorb moisture from the air
and contaminate the fluid.
CAUTION: Never use any type of a petroleum-
based fluid in the brake hydraulic system. Use of
such type fluids will result in seal damage of the
vehicle brake hydraulic system causing a failure of
the vehicle brake system. Petroleum based fluids
would be items such as engine oil, transmission
fluid, power steering fluid, etc.
BRAKE ACTUATION SYSTEM
ACTUATION:
Vacuum Operated Power Brakes.....Standard
Hydraulic System.......Dual-Diagonally Split
BRAKE PEDAL:
Pedal Ratio..........................3.41
POWER BRAKE BOOSTER:
Make/Type..................Bosch/Vacuum
Mounting Studs.................. M8x1.25
Diaphragm Size/Type........ 205mmTandem
MASTER CYLINDER ASSEMBLY:
Type ........................Dual Tandem
Body Material...........Anodized Aluminum
Reservoir Material.............Polypropelene
MASTER CYLINDER BORE STROKE AND
SPLIT:
NonABS ..............22.23 mm x 34.0 mm
(0.875 in. x 1.34 in.)
ABS . . 23.82 mm x 34.0 mm (0.937 in. x 1.34 in.)
Displacement Split.................. 50/50MASTER CYLINDER FLUID OUTLET PORTS:
Tube Fitting Type...... SAE45ÉInverted Flare
W/ABS - Primary Tube Nut
Thread........................7/16 in.±24
W/ABS - Secondary Tube Nut
Thread........................ 3/8in.±24
W/O ABS - All Tube Nut Threads....7/16 in.±24
ABS HYDRAULIC CONTROL UNIT:
Hydraulic Tube Fitting
Type................ SAE45ÉInverted Flare
All Tube Nut Threads............7/16 in.±24
PROPORTIONING VALVE:
Material.......................Aluminum
Function.....Hydraulic Pressure Proportioning
BRAKE FASTENER TORQUE SPECIFICATIONS
DESCRIPTION TORQUE
BRAKE TUBES:
Tube Nuts............... 17N´m(145 in. lbs.)
MASTER CYLINDER:
Mounting Nuts.......... 28N´m(250 in. lbs.)
POWER BRAKE BOOSTER:
Mounting Nuts.......... 34N´m(300 in. lbs.)
DISC BRAKE CALIPER:
Caliper Banjo Bolt......... 48N´m(35ft.lbs.)
Guide Pin Bolts.......... 22N´m(192 in. lbs.)
Bleeder Screw........... 15N´m(125 in. lbs.)
WHEEL CYLINDER (REAR):
Mounting Bolts.......... 13N´m(115in.lbs.)
Bleeder Screw............ 10N´m(80in.lbs.)
DRUM BRAKE SHOE SUPPORT PLATE
(REAR):
Mounting Bolts........... 75N´m(55ft.lbs.)
DISC BRAKE ADAPTER (REAR):
Mounting Bolts........... 75N´m(55ft.lbs.)
HUB AND BEARING (REAR):
Retaining Nut.......... 217N´m(160 ft. lbs.)
PARKING BRAKE:
Lever Mounting Nuts..... 28N´m(250 in. lbs.)
TIRE AND WHEEL:
Wheel Mounting Nut...........109±150 N´m
(80±110 ft. lbs.)
INTEGRATED CONTROL UNIT:
Mounting Bolts........... 11N´m(97in.lbs.)
CAB Mounting bolts........ 2N´m(17in.lbs.)
Bracket-to-Frame Rail Bolts.......... 23N´m
(200 in. lbs.)
WHEEL SPEED SENSOR:
Head Mounting bolt...... 12N´m(105 in. lbs.)
PLBRAKES 5 - 63

ANTILOCK BRAKE SYSTEM
TABLE OF CONTENTS
page page
DESCRIPTION AND OPERATION
ANTILOCK BRAKE SYSTEM OPERATION......65
ANTILOCK BRAKE SYSTEM COMPONENTS....66
ELECTRONIC BRAKE DISTRIBUTION.........69
TRACTION CONTROL SYSTEM..............70
HYDRAULIC CIRCUITS AND VALVE
OPERATION...........................71
DIAGNOSIS AND TESTING
SERVICE WARNINGS AND CAUTIONS........74
ABS GENERAL DIAGNOSTICS INFORMATION . . 74
ABS WIRING DIAGRAM INFORMATION........74
ABS VEHICLE TEST DRIVE.................74
ABS ELECTRONIC DIAGNOSIS..............75
TONE WHEEL...........................76
BRAKE FLUID CONTAMINATION.............76
SERVICE PROCEDURES
BRAKE FLUID LEVEL CHECKING............77ANTILOCK BRAKE SYSTEM BLEEDING.......77
MASTER CYLINDER BLEEDING.............77
REMOVAL AND INSTALLATION
SERVICE WARNINGS AND CAUTIONS........78
MASTER CYLINDER......................78
INTEGRATED CONTROL UNIT...............79
WHEEL SPEED SENSOR (FRONT)...........81
WHEEL SPEED SENSOR (REAR)............83
DISASSEMBLY AND ASSEMBLY
INTEGRATED CONTROL UNIT...............84
SPECIFICATIONS
TONE WHEEL RUNOUT....................85
WHEEL SPEED SENSOR-TO-TONE WHEEL
CLEARANCE...........................85
BRAKE FASTENER TORQUE
SPECIFICATIONS.......................85
DESCRIPTION AND OPERATION
ANTILOCK BRAKE SYSTEM OPERATION
This section covers the physical and operational
descriptions, and the on-car service procedures for
the Mark 20e Antilock Brake System (ABS) with
traction control. It is the only antilock brake system
available on this vehicle.
The purpose of the antilock brake system is to pre-
vent wheel lockup under braking conditions on virtu-
ally any type of road surface. Antilock braking is
desirable because a vehicle that is stopped without
locking the wheels retains directional stability and
some steering capability. This allows the driver to
retain greater control of the vehicle during braking.
The traction control system reduces wheel slip and
maintains traction at the driving speeds below 56
kph (35 mph) when road conditions call for traction
assistance. Refer to TRACTION CONTROL SYSTEM
in this section for more information.
Vehicles equipped with ABS use electronic brake
distribution (EBD) to balance front-to-rear braking
when the brakes are applied in the partial braking
range. Refer to ELECTRONIC BRAKE DISTRIBU-
TION in this section for more information.
There are a few performance characteristics of the
Mark 20e Antilock Brake System that may at first
seem abnormal, but in fact are normal. These char-
acteristics are described below.
NORMAL BRAKING
Under normal braking conditions, the ABS func-
tions the same as a standard base brake system with
a diagonally split master cylinder and conventional
vacuum assist.
ABS BRAKING
ABS operation is available at all vehicle speeds
above 3±5 mph. If a wheel locking tendency is
detected during a brake application, the brake sys-
tem enters the ABS mode. During ABS braking,
hydraulic pressure in the four wheel circuits is mod-
ulated to prevent any wheel from locking. Each
wheel circuit is designed with a set of electric sole-
noids to allow modulation, although for vehicle sta-
bility, both rear wheel solenoids receive the same
electrical signal. Wheel lockup may be perceived at
the very end of an ABS stop and is considered nor-
mal.
During an ABS stop, the brakes hydraulic system
is still diagonally split. However, the brake system
pressure is further split into four control channels.
During antilock operation of the vehicle's brake sys-
tem, the wheels are controlled independently and are
on separate control channels.
The system can build, hold and release pressure at
each wheel, depending on signals generated by the
wheel speed sensors (WSS) at each wheel and
received at the controller antilock brake (CAB).
PLBRAKES 5 - 65

NOISE AND BRAKE PEDAL FEEL
During ABS braking, some brake pedal movement
may be felt. In addition, ABS braking will create
ticking, popping, or groaning noises heard by the
driver. This is normal and is due to pressurized fluid
being transferred between the master cylinder and
the brakes. If ABS operation occurs during hard
braking, some pulsation may be felt in the vehicle
body due to fore-and-aft movement of the suspension
as brake pressures are modulated.
At the end of an ABS stop, ABS is turned off when
the vehicle is slowed to a speed of 3±4 mph. There
may be a slight brake pedal drop anytime that the
ABS is deactivated, such as at the end of the stop
when the vehicle speed is less than 3 mph or during
an ABS stop where ABS is no longer required. These
conditions exist when a vehicle is being stopped on a
road surface with patches of ice, loose gravel, or sand
on it. Also, stopping a vehicle on a bumpy road sur-
face activates ABS because of the wheel hop caused
by the bumps.
TIRE NOISE AND MARKS
Although the ABS system prevents complete wheel
lockup, some wheel slip is desired in order to achieve
optimum braking performance. Wheel slip is defined
as follows: 0 percent slip means the wheel is rolling
freely and 100 percent slip means the wheel is fully
locked. During brake pressure modulation, wheel slip
is allowed to reach up to 25±30 percent. This means
that the wheel rolling velocity is 25±30 percent less
than that of a free rolling wheel at a given vehicle
speed. This slip may result in some tire chirping,
depending on the road surface. This sound should not
be interpreted as total wheel lockup.
Complete wheel lockup normally leaves black tire
marks on dry pavement. The ABS will not leave dark
black tire marks since the wheel never reaches a
fully locked condition. However, tire marks may be
noticeable as light patched marks.
START-UP CYCLE
When the ignition is turned on, a popping sound
and a slight brake pedal movement may be noticed.
The ABS warning lamp will also be on for up to 5
seconds after the ignition is turned on. When the
vehicle is first driven off, a humming may be heard
or felt by the driver at approximately 20±40 kph
(12±25 mph). All of these conditions are a normal
function of ABS as the system is performing a diag-
nosis check.
PREMATURE ABS CYCLING
Symptoms of premature ABS cycling include: click-
ing sounds from the solenoid valves; pump/motor
running; and pulsations in the brake pedal. Prema-ture ABS cycling can occur at any braking rate of the
vehicle and on any type of road surface. Neither the
red BRAKE warning lamp, nor the amber ABS warn-
ing lamp, illuminate and no fault codes are stored in
the CAB.
Premature ABS cycling is a condition that needs to
be correctly assessed when diagnosing problems with
the antilock brake system. It may be necessary to use
a DRB scan tool to detect and verify premature ABS
cycling.
Check the following common causes when diagnos-
ing premature ABS cycling: damaged tone wheels;
incorrect tone wheels; damaged steering knuckle
wheel speed sensor mounting bosses; loose wheel
speed sensor mounting bolts; excessive tone wheel
runout; or an excessively large tone wheel-to-wheel
speed sensor air gap. Give special attention to these
components when diagnosing a vehicle exhibiting
premature ABS cycling.
After diagnosing the defective component, repair or
replace it as required. When the component repair or
replacement is completed, test drive the vehicle to
verify that premature ABS cycling has been cor-
rected.
ANTILOCK BRAKE SYSTEM COMPONENTS
The following is a detailed description of the
antilock brake system components. For information
on servicing base brake system components used in
conjunction with these components, see the BASE
BRAKE SYSTEM found at the beginning of this ser-
vice manual group.
MASTER CYLINDER
A vehicle equipped with ABS uses a different mas-
ter cylinder than a vehicle that is not equipped with
ABS. Vehicles equipped with ABS use a center port
master cylinder with only two outlet ports (Fig. 1).
The brake tubes from the primary and secondary
outlet ports on the master cylinder go directly to the
integrated control unit (ICU).
The master cylinder mounts to the power brake
booster in the same manner a non-ABS master cylin-
der does.
INTEGRATED CONTROL UNIT (ICU)
The hydraulic control unit (HCU) and the control-
ler antilock brake (CAB) used with this antilock
brake system are combined (integrated) into one
unit, which is called the integrated control unit (ICU)
(Fig. 2). The ICU is located on the driver's side of the
vehicle, and is mounted to the left front frame rail
below the master cylinder (Fig. 1).
5 - 66 BRAKESPL
DESCRIPTION AND OPERATION (Continued)

AMBER ABS WARNING LAMP
The amber ABS warning lamp is located in the
instrument cluster. The purpose of the warning lamp
is discussed in detail below.
When the ignition key is turned to the ON posi-
tion, the amber ABS warning lamp is lit until the
CAB completes its self-tests and turns off the lamp
(approximately 4 seconds). The amber ABS warning
lamp will illuminate when the CAB detects a condi-
tion that results in the shutdown of ABS function.
The CAB sends a message to the mechanical instu-
ment cluster (MIC) instructing it to turn on the
amber ABS warning lamp.
Under most conditions, when the amber ABS warn-
ing lamp is on, only the ABS function of the brake
system is affected; The electronic brake distribution
(EBD), the base brake system and the ability to stop
the vehicle are not affected.
WHEEL SPEED SENSOR (WSS)
At each wheel of the vehicle there is one wheel
speed sensor (WSS) and one tone wheel (Fig. 3) (Fig.
4) (Fig. 5) (Fig. 6). Each front wheel speed sensor is
attached to a boss in the steering knuckle. The front
tone wheel is part of the driveshaft outboard con-
stant velocity joint. The rear wheel speed sensor is
mounted to the rear disc brake adapter. The rear
tone wheel is an integral part of the rear wheel hub
and bearing.
The wheel speed sensor operates on electronic
energy supplied by the CAB and outputs a square
wave signal whose current alternates between two
constant levels. Its frequency is proportional to the
speed of the tone wheel. The output is available as
long as the sensor is powered and its state (high or
low) corresponds to the presence or absence of tone
wheel teeth. The output signal is sent to the CAB. If
a wheel locking tendency is detected by the CAB, it
will then modulate hydraulic pressure via the HCU
to prevent the wheel(s) from locking.
Correct ABS operation is dependent on accurate
wheel speed signals. The vehicle's tires and wheels
all must be the same size and type to generate accu-
rate signals. Variations in tire and wheel size can
produce inaccurate wheel speed signals.
Improper speed sensor-to-tone wheel clearance can
cause erratic speed sensor signals. The speed sensor
air gap is not adjustable, but should be checked when
applicable. Wheel speed sensor-to-tone wheel clear-
ance specifications can be found in the SPECIFICA-
TIONS section within this section in this service
manual group.
ELECTRONIC BRAKE DISTRIBUTION
Vehicles equipped with ABS use electronic brake
distribution (EBD) to balance front-to-rear braking.The EBD is used in place of a rear proportioning
valve. The EBD system uses the ABS system to con-
trol the slip of the rear wheels in partial braking
range. The braking force of the rear wheels is con-
trolled electronically by using the inlet and outlet
valves located in the integrated control unit.
Upon entry into EBD the inlet valve for the rear
brake circuit is switched on so that the fluid supply
from the master cylinder is shut off. In order to
decrease the rear brake pressure, the outlet valve for
Fig. 3 Left Front Wheel Speed Sensor
1 ± LEFT FRONT WHEEL SPEED SENSOR
2 ± TONE WHEEL
Fig. 4 Right Front Wheel Speed Sensor
1 ± RIGHT FRONT WHEEL SPEED SENSOR
2 ± TONE WHEEL
PLBRAKES 5 - 69
DESCRIPTION AND OPERATION (Continued)

ABS ELECTRONIC DIAGNOSIS
The following information is presented to give the
technician a general background on the diagnostic
capabilities of the ABS system. Complete electronic
diagnosis of the ABS system used on this vehicle is
covered in the Chassis Diagnostic Procedures manual.
Electronic diagnosis of the ABS system used on
this vehicle is performed using the DRBIIItscan
tool. The vehicle's scan tool diagnostic connector is
located under the steering column lower cover, to the
left side of the steering column (Fig. 10).
ABS SELF-DIAGNOSIS
The ABS system is equipped with a self-diagnosis
capability, which may be used to assist in the isola-
tion of ABS faults. The features are described below.
START-UP CYCLE
The self-diagnosis ABS start-up cycle begins when
the ignition switch is turned to the ON position.
Electrical checks are completed on ABS components,
including the CAB, solenoid continuity, and the relay
system operation. During this check the amber ABS
warning lamp is turned on for approximately 5 sec-
onds and the brake pedal may emit a popping sound,
moving slightly when the solenoid valves are
checked.
DRIVE-OFF CYCLE
The first time the vehicle is set in motion after an
ignition off/on cycle, the drive-off cycle occurs. This
cycle is performed when the vehicle reaches a speed
of approximately 20 kph (12 mph.).²The pump/motor is briefly activated to verify
function. When the pump/motor is briefly activated, a
whirling or buzzing sound may be heard by the
driver. This sound is normal, indicating the pump/
motor is running.
²The wheel speed sensor output correct operating
range is verified.
ONGOING TESTS
While the system is operating, these tests are per-
formed on a continuous basis:
²solenoid continuity
²wheel speed sensor continuity
²wheel speed sensor output
DIAGNOSTIC TROUBLE CODES (DTC's)
Diagnostic trouble codes (DTC's) are kept in the
controller's memory until either erased by the techni-
cian using the DRB, or erased automatically after
3500 miles or 255 ignition key cycles, whichever
occurs first. DTC's are retained by the controller
even if the ignition is turned off or the battery is dis-
connected. More than one DTC can be stored at a
time. When accessed, the number of occurrences
(ignition key cycles) and the DTC that is stored are
displayed. Most functions of the CAB and the ABS
system can be accessed by the technician for testing
and diagnostic purposes using the DRB.
LATCHING VERSUS NON-LATCHING DIAGNOSTIC TROUBLE
CODES
Some DTC's detected by the CAB are ªlatchingº
codes. The DTC is latched and ABS braking is dis-
abled until the ignition switch is reset. Thus, ABS
braking is non-operational even if the original DTC
has disappeared. Other DTC's are non-latching. Any
warning lamps that are turned on are only turned on
as long as the DTC condition exists; as soon as the
condition goes away, the amber ABS warning lamp is
turned off, although, in most cases, a DTC is set.
INTERMITTENT DIAGNOSTIC TROUBLE CODES
As with virtually any electronic system, intermit-
tent electrical problems in the ABS system may be
difficult to accurately diagnose. Most intermittent
electrical problems are caused by faulty electrical
connections or wiring. A visual inspection should be
done before trying to diagnose or service the antilock
brake system; this will eliminate unnecessary diag-
nosis and testing time. Perform a visual inspection
for loose, disconnected, damaged, or misrouted wires
or connectors; include the following components and
areas of the vehicle in the inspection.
(1) Inspect fuses in the power distribution center
(PDC) and the wiring junction block. Verify that all
fuses are fully inserted into the PDC and wiring
Fig. 10 ABS System Diagnostic Connector Location
1 ± DRIVER AIRBAG MODULE
2 ± PASSENGER AIRBAG MODULE
3 ± DATA LINK CONNECTOR
PLBRAKES 5 - 75
DIAGNOSIS AND TESTING (Continued)